We present an analytical model for cross-Kerr nonlinear coefficient in a four-level N-type atomic medium under Doppler broadening.The model is applied to87 Rb atoms to analyze the dependence of the cross-Kerr nonlinea...We present an analytical model for cross-Kerr nonlinear coefficient in a four-level N-type atomic medium under Doppler broadening.The model is applied to87 Rb atoms to analyze the dependence of the cross-Kerr nonlinear coefficient on the external light field and the temperature of atomic vapor.The analysis shows that in the absence of electromagnetically induced transparency(EIT)the cross-Kerr nonlinear coefficient is zero,but it is significantly enhanced when the EIT is established.It means that the cross-Kerr effect can be turned on/off when the external light field is on or off.Simultaneously,the amplitude and the sign of the cross-Kerr nonlinear coefficient are easily changed according to the intensity and frequency of the external light field.The amplitude of the cross-Kerr nonlinear coefficient remarkably decreases when the temperature of atomic medium increases.The analytical model can be convenient to fit experimental observations and applied to photonic devices.展开更多
Nonreciprocal microwave devices,in which the transmission of waves is non-symmetric between two ports,are indispensable for the manipulation of information processing and communication.In this work,we show the nonreci...Nonreciprocal microwave devices,in which the transmission of waves is non-symmetric between two ports,are indispensable for the manipulation of information processing and communication.In this work,we show the nonreciprocal microwave transmission in a cavity magnonic system under the joint mechanism of phase modulation and magnon Kerr nonlinearity effect.In contrast to the schemes based on the standard phase modulation or magnon Kerr nonlinearity,we find that the joint mechanism enables the nonreciprocal transmission even at low power and makes us obtain a high nonreciprocal isolation ratio.Moreover,when two microwave modes are coupled to the magnon mode via a different coupling strength,the presented strong nonreciprocal response occurs,and it makes the nonreciprocal transmission manipulating by the magnetic field within a large adjustable range possible,which overcomes narrow operating bandwidths.This study may provide promising opportunities to realize nonreciprocal structures for wave transmission.展开更多
We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelen...We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.展开更多
We show that incoherently coupled soliton pairs can exist in nonlocal Kerr-type nonlinear media. Such solitons can propagate in bright--bright, dark--dark, and gray--gray configurations. When the nonlocal nonlinearity...We show that incoherently coupled soliton pairs can exist in nonlocal Kerr-type nonlinear media. Such solitons can propagate in bright--bright, dark--dark, and gray--gray configurations. When the nonlocal nonlinearity is absent, these bright--bright and dark--dark soliton pairs are those observed previously in local Kerr-type nonlinear media. Our analysis indicates that for a self-focusing nonlinearity the intensity full width half maximum （FWHM） of the bright--bright pair components increases with the degree of nonlocality of the nonlinear response, whereas for a self-defocusing nonlinearity the intensity FWHM of the dark--dark and gray--gray pair components decreases with the increase in the degree of nonlocality of the nonlinear response. The stability of these soliton pairs has been investigated numerically and it has been found that they are stable.展开更多
The high degree of freedom and novel nonlinear phenomena of multimode fiber are attracting attention. In this work,we demonstrate a spatiotemporal mode-locked multimode fiber laser, which relies on microfiber knot res...The high degree of freedom and novel nonlinear phenomena of multimode fiber are attracting attention. In this work,we demonstrate a spatiotemporal mode-locked multimode fiber laser, which relies on microfiber knot resonance(MKR) via dissipative four-wave-mixing(DFMW) to achieve high-repetition-rate pulses. Apart from that, DFMW mode locking with switchable central wavelengths can also be obtained. It was further found that high pulse energy induced nonlinear effect of the dominant mode-locking mechanism transforming from DFMW to nonlinear Kerr beam cleaning effect(NL-KBC). The experimental results are valuable for further comprehending the dynamic characteristics of spatiotemporal mode-locked multimode fiber lasers, facilitating them much more accessible for applications.展开更多
Ultrafine PbS particles with different sizes have been prepared in perfluorocarboxylatedcation-exchanged films.The variation of PbS particle size was clarified by absorption spectraand TEM graphs.Time-resolved optical...Ultrafine PbS particles with different sizes have been prepared in perfluorocarboxylatedcation-exchanged films.The variation of PbS particle size was clarified by absorption spectraand TEM graphs.Time-resolved optical Kerr effects were measured by femisecond pump-probe techniques.Optical Kerr effect response time was estimated to be less than 165 fs.Athird-order optical nonlinearity of～10<sup>-12</sup>esu for PbS particles was obtained and it wasfound that it increases with the decrease of particle sizes,showing the influence of quantumconfined effect on optical nonlinear behavious of Ultrafine particles.展开更多
This paper has made a theoretical study of enhanced transmission through a gold grating with arrays of subwavelength slits filled with nonlinear Kerr medium. The results of the research are based on rigorous finite-di...This paper has made a theoretical study of enhanced transmission through a gold grating with arrays of subwavelength slits filled with nonlinear Kerr medium. The results of the research are based on rigorous finite-difference time domain calculations. The resonance transmission peaks in the investigated wavelength range are produced as a result of the surface plasmon resonance collaborated with the localized waveguide resonance. The paper also gives a detailed analysis of the influence exerted by various factors: thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays and the incident intensity to the transmission. It is found that the small changes of parameters such as medium thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays as well as the incident intensity can bring great changes of lateral shift and magnitude variation of the transmission resonance peaks. The report proposes that these phenomena can be applied to designing precise optical switches.展开更多
We demonstrate a novel approach to achieve wavelength-tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on the nonlinear Kerr beam clean-up effect.This saturable absorber wa...We demonstrate a novel approach to achieve wavelength-tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on the nonlinear Kerr beam clean-up effect.This saturable absorber was formed by a single-mode fiber spliced to a graded-index multimode fiber,and its tunable band-pass filter effect is described by a numerical model.By adjusting the bending condition of the graded-index multimode fiber,the laser could produce dissipative soliton pulses with their central wavelength tunable from 1040 nm to 1063 nm.The pulse duration of the output laser could be compressed externally to 791 fs,and the signal to noise ratio of its radio frequency spectrum was measured to be 75.5 dB.展开更多
The imaging theory of Raman induced Kerr effect spectroscopy (RIKES) in nonlinear confocal microscopy is presented in this paper. Three-dimensional point spread function (3D-PSF) of RIKES nonlinear confocal microscopy...The imaging theory of Raman induced Kerr effect spectroscopy (RIKES) in nonlinear confocal microscopy is presented in this paper. Three-dimensional point spread function (3D-PSF) of RIKES nonlinear confocal microscopy in isotropic media is derived with Fourier imaging theory and RIKES theory. The impact of nonlinear property of RIKES on the spatial resolution and imaging properties of confocal microscopy have been analyzed in detail. It is proved that RIKES nonlinear confocal microscopy can simultaneously provide more information than two-photon confocal microscopy concerning molecular vibration mode, vibration orientation and optically induced molecular reorientation, etc. It is shown that RIKES nonlinear confocal microscopy significantly enhances the spatial resolution and imaging quality of confocal microscopy and achieves much higher resolution than that of two-photon confocal microscopy.展开更多
基金supported by Vietnam’s Ministry of Education and Training under Grant No.B2018-TDV-01SP。
文摘We present an analytical model for cross-Kerr nonlinear coefficient in a four-level N-type atomic medium under Doppler broadening.The model is applied to87 Rb atoms to analyze the dependence of the cross-Kerr nonlinear coefficient on the external light field and the temperature of atomic vapor.The analysis shows that in the absence of electromagnetically induced transparency(EIT)the cross-Kerr nonlinear coefficient is zero,but it is significantly enhanced when the EIT is established.It means that the cross-Kerr effect can be turned on/off when the external light field is on or off.Simultaneously,the amplitude and the sign of the cross-Kerr nonlinear coefficient are easily changed according to the intensity and frequency of the external light field.The amplitude of the cross-Kerr nonlinear coefficient remarkably decreases when the temperature of atomic medium increases.The analytical model can be convenient to fit experimental observations and applied to photonic devices.
基金the National Natural Science Foundation of China(Grant Nos.12105092 and 12022507)Program for Innovative Teams of Outstanding Young and Middle-aged Researchers in the Higher Education Institution of Hubei Province(No.T2020014).
文摘Nonreciprocal microwave devices,in which the transmission of waves is non-symmetric between two ports,are indispensable for the manipulation of information processing and communication.In this work,we show the nonreciprocal microwave transmission in a cavity magnonic system under the joint mechanism of phase modulation and magnon Kerr nonlinearity effect.In contrast to the schemes based on the standard phase modulation or magnon Kerr nonlinearity,we find that the joint mechanism enables the nonreciprocal transmission even at low power and makes us obtain a high nonreciprocal isolation ratio.Moreover,when two microwave modes are coupled to the magnon mode via a different coupling strength,the presented strong nonreciprocal response occurs,and it makes the nonreciprocal transmission manipulating by the magnetic field within a large adjustable range possible,which overcomes narrow operating bandwidths.This study may provide promising opportunities to realize nonreciprocal structures for wave transmission.
文摘We propose and analyze a submicron stub-assisted ultrafast all-optical plasmonic switch based on nonlinear MIM waveguide. It is constructed by two silicon stub filters sandwiched by silver cladding. The signal wavelength is assumed to be 1550 nm. The simulation results show a ?14.66 dB extinction ratio. Downscaling the silicon waveguide in MIM structure leads to enhancement of the effective Kerr nonlinearity due to tight mode confinement. Also, using O+ ions implanted into silicon, the switching time less than 10 ps and a delay time less than 8 fs are achieved. The overall length of the switch is 550 nm.
基金supported by the National Natural Science Foundation of China (Grant No. 10674176)
文摘We show that incoherently coupled soliton pairs can exist in nonlocal Kerr-type nonlinear media. Such solitons can propagate in bright--bright, dark--dark, and gray--gray configurations. When the nonlocal nonlinearity is absent, these bright--bright and dark--dark soliton pairs are those observed previously in local Kerr-type nonlinear media. Our analysis indicates that for a self-focusing nonlinearity the intensity full width half maximum （FWHM） of the bright--bright pair components increases with the degree of nonlocality of the nonlinear response, whereas for a self-defocusing nonlinearity the intensity FWHM of the dark--dark and gray--gray pair components decreases with the increase in the degree of nonlocality of the nonlinear response. The stability of these soliton pairs has been investigated numerically and it has been found that they are stable.
基金Project partially supported by the National Natural Science Foundation of China (Grant Nos. 91950105 and 62175116)the 1311 Talent Plan of Nanjing University of Posts and Telecommunications。
文摘The high degree of freedom and novel nonlinear phenomena of multimode fiber are attracting attention. In this work,we demonstrate a spatiotemporal mode-locked multimode fiber laser, which relies on microfiber knot resonance(MKR) via dissipative four-wave-mixing(DFMW) to achieve high-repetition-rate pulses. Apart from that, DFMW mode locking with switchable central wavelengths can also be obtained. It was further found that high pulse energy induced nonlinear effect of the dominant mode-locking mechanism transforming from DFMW to nonlinear Kerr beam cleaning effect(NL-KBC). The experimental results are valuable for further comprehending the dynamic characteristics of spatiotemporal mode-locked multimode fiber lasers, facilitating them much more accessible for applications.
基金the High Technology Research and Development Programme of China and Academia Sinica.
文摘Ultrafine PbS particles with different sizes have been prepared in perfluorocarboxylatedcation-exchanged films.The variation of PbS particle size was clarified by absorption spectraand TEM graphs.Time-resolved optical Kerr effects were measured by femisecond pump-probe techniques.Optical Kerr effect response time was estimated to be less than 165 fs.Athird-order optical nonlinearity of～10<sup>-12</sup>esu for PbS particles was obtained and it wasfound that it increases with the decrease of particle sizes,showing the influence of quantumconfined effect on optical nonlinear behavious of Ultrafine particles.
基金supported by the National Natural Science Foundation of China (Grant No. 60708014)the Distinguished Youth Foundation of Hu-nan Province (Grant No. 03JJY1008)+2 种基金the Science Foundation for Post-doctorate of China (Grant No. 2004035083)the Natural Science Foundation of Hunan Province (Grant No. 06JJ2034)the Excellent Doctorate Dissertation Foundation of Central South University (Grant No. 2008yb039)
文摘This paper has made a theoretical study of enhanced transmission through a gold grating with arrays of subwavelength slits filled with nonlinear Kerr medium. The results of the research are based on rigorous finite-difference time domain calculations. The resonance transmission peaks in the investigated wavelength range are produced as a result of the surface plasmon resonance collaborated with the localized waveguide resonance. The paper also gives a detailed analysis of the influence exerted by various factors: thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays and the incident intensity to the transmission. It is found that the small changes of parameters such as medium thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays as well as the incident intensity can bring great changes of lateral shift and magnitude variation of the transmission resonance peaks. The report proposes that these phenomena can be applied to designing precise optical switches.
文摘We demonstrate a novel approach to achieve wavelength-tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on the nonlinear Kerr beam clean-up effect.This saturable absorber was formed by a single-mode fiber spliced to a graded-index multimode fiber,and its tunable band-pass filter effect is described by a numerical model.By adjusting the bending condition of the graded-index multimode fiber,the laser could produce dissipative soliton pulses with their central wavelength tunable from 1040 nm to 1063 nm.The pulse duration of the output laser could be compressed externally to 791 fs,and the signal to noise ratio of its radio frequency spectrum was measured to be 75.5 dB.
基金the Natural Science Foundation of Guangdong Province of China (Grant No. 05005926)the Plan Project of Science and Technology of Guangzhou City (Grant No. 2007J1-C0011)Open Foundation of the Key Laboratory of Laser Life Science,Ministry of Education of China(2007-05)
文摘The imaging theory of Raman induced Kerr effect spectroscopy (RIKES) in nonlinear confocal microscopy is presented in this paper. Three-dimensional point spread function (3D-PSF) of RIKES nonlinear confocal microscopy in isotropic media is derived with Fourier imaging theory and RIKES theory. The impact of nonlinear property of RIKES on the spatial resolution and imaging properties of confocal microscopy have been analyzed in detail. It is proved that RIKES nonlinear confocal microscopy can simultaneously provide more information than two-photon confocal microscopy concerning molecular vibration mode, vibration orientation and optically induced molecular reorientation, etc. It is shown that RIKES nonlinear confocal microscopy significantly enhances the spatial resolution and imaging quality of confocal microscopy and achieves much higher resolution than that of two-photon confocal microscopy.
